proxy 127 virus removal

Currently on site we have the proxy 127 virus. it is effecting over half of our campus. Not sure how it got in but the only way i can see to fix it at the moment to to run a virus scan. Scans have been ran using our Virus network management (Sophos) But this is not working. We cant really go round every computer as there is over 1000 Computers. Is anyone aware of any scripts we can run using GPO to help Remove this?